Role of inhibition of osteogenesis function by Sema4D/Plexin-B1 signaling pathway in skeletal fluorosis in vitro

• Published in: Journal of Huazhong University of Science and Technology. Medical sciences Vol. 35; no. 5; pp. 712 - 715
• Main Authors: Liu, Xiao-li, Song, Jing, Liu, Ke-jian, Wang, Wen-peng, Xu, Chang, Zhang, Yu-zeng, Liu, Yun
• Format: Journal Article
• Language: English
• Published: Wuhan Huazhong University of Science and Technology 01.10.2015; Zibo Center for Disease Control and Prevention, Zibo 255026, China%Department of Epidemiology and Biostatistics, Health Science Center, Peking University, Beijing 100191, China%Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
• Subjects: Animals; Antigens, CD - genetics; Antigens, CD - metabolism; Cell Proliferation - drug effects; Feedback, Physiological; Fetus; Fluorides - pharmacology; Gene Expression Regulation, Developmental; GTPase-Activating Proteins - genetics; GTPase-Activating Proteins - metabolism; Medicine; Medicine & Public Health; Osteoblasts - drug effects; Osteoblasts - metabolism; Osteoblasts - pathology; Osteoclasts - drug effects; Osteoclasts - metabolism; Osteoclasts - pathology; Osteogenesis - drug effects; Osteogenesis - genetics; Osteoprotegerin - genetics; Osteoprotegerin - metabolism; RANK Ligand - genetics; RANK Ligand - metabolism; Rats; Receptor Activator of Nuclear Factor-kappa B - genetics; Receptor Activator of Nuclear Factor-kappa B - metabolism; Receptors, Cell Surface - genetics; Receptors, Cell Surface - metabolism; rho-Associated Kinases - genetics; rho-Associated Kinases - metabolism; rhoA GTP-Binding Protein - genetics; rhoA GTP-Binding Protein - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; Semaphorins - genetics; Semaphorins - metabolism; Signal Transduction; Transforming Growth Factor beta1 - genetics; Transforming Growth Factor beta1 - metabolism; fluoride; osteoblast; osteoclast; skeletal fluorosis; semaphorin4D
• ISSN: 1672-0733; 1993-1352
• DOI: 10.1007/s11596-015-1495-1

Summary Skeletal fluorosis is a chronically metabolic bone disease with extensive hyperostosis osteosclerosis caused by long time exposure to fluoride. Skeletal fluorosis brings about a series of abnormal changes of the extremity, such as joint pain, joint stiffness, bone deformity, etc. Differentiation and maturation of osteoblasts were regulated by osteoclasts via Sema4D/Plexin-B1 signaling pathway. Furthermore, the differentiation and maturation of osteoclasts are conducted by osteoblasts via RANKL/RANK/OPG pathway. Both of these processes form a feedback circuit which is a key link in skeletal fluorosis. In this study, an osteoblast-osteoclast co-culture model in vitro was developed to illustrate the mechanism of skeletal fluorosis. With the increase of fluoride concentration, the expression level of Sema4D was decreased and TGF-β1 was increased continuously. OPG/RANKL mRNA level, however, increased gradually. On the basis of that, the inhibition of Sema4D/Plexin-B1/RhoA/ROCK signaling pathway caused by fluoride promoted the level of TGF-β1 and activated the proliferation of osteoblasts. In addition, osteroprotegerin (OPG) secreted by osteoblasts was up-regulated by fluoride. The competitive combination of OPG and RANKL was strengthened and the combination of RANKL and RANK was hindered. And then the differentiation and maturation of osteoclasts were inhibited, and bone absorption was weakened, leading to skeletal fluorosis.